Circuit breaker



Oct. 8, 1940. H. H. WILLMANN 2,217,462

CIRCUIT BREAKER Filed Aug. 2, 1937 2 Sheets-Sheet l 53 Insulation WITNESSES: S v INVENTOR W/M Ham/iA/fl/mafln @MWW/M BY i X/ATTORNZ Oct. 8, 1940.

H. H. WILLMANN 2,217,462

cmcurr BREAKEB Filed Aug. 2, 1937 2 Sheets-Sheet 2 Patented Oct. 8, 1940 CIRCUIT BREAKER Hans H. Willmann, Berlin-Charlottenburg, Germany, assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation oi Pennsylvania Application August 2, 1937, Serial No. 157,028

In G

- 10 Claims.

The invention relates to circuit breakers in general and more particularly to circuit breakers of the type used for controlling lighting and moderate power distribution networki systems, in which the breaker is manually operable to open and to close the circuit and automatically operable to open the circuit in response to predetermined overload conditions.

To be commercially successful, the circuit breaker for such use must be capable of interrupting largeamounts of electric power due to the interconnection of the numerous circuits of the system. The trip device of the breaker must be capable of distinguishing between overloads of differing magnitude so that it will open the breaker immediately upon the occurrence of a short circuit condition, and only after a predetermined period of time in response to overloads of moderate magnitude in order to prevent undue interruptions of service in response to transitorylower'magnitude overloads. It is desirable that the actuating mechanism of the breaker open and close the contacts with a snap action in order to minimize arcing; and that the contacts b'e trip-free of the operating handle so that the breaker may be tripped open even though the handle is held in the-closed position. The tripping and actuating mechanisms must be extremely accurate in operation and must maintain their accuracy for a considerable period of time. This means that only very small tolerances can be permitted in the manufacture of the breaker. In addition to the above requirements, the circuit breaker must be simple, safe and reliable in operation, compact, and inexpensive to manufacture.

An object of the invention is the provision of an improved circuit breaker that will satisfactorily meet all of the above-mentioned requirements.

Another object of the invention is the provision of a circuit breaker with an improved actuating mechanism for actuating the contact means to openand close the circuit,

Another object of the invention is the provision of a circuit breaker with an improved actuating mechanism which provides for greater safety of operation of the breaker and which prevents improper operation of the same.

Another object of the invention is the provision of an improved actuating mechanism for a circuit breaker for opening the contacts with a snap action, and which is operable to close the contacts with a snap action at a predetermined point in the closing movement of an operating simplified tripping mechanism which is manually ermany August 3, 1936 member regardless of the speed of movement of the member.

Another object of the invention is the provision of a circuit breaker with an improved and operable to open the breaker contacts and automatically operable to open the breaker contacts in response to predetermined overload conditions.

Another object of the invention is the provision of ,a circuit breaker having a casing con- 10 V sisting of several sections suitably recessed to receive the various parts of the breaker, with an improved mounting means for securing the tripping and actuating mechanism and the combined tripping and blowout electromagnet to one of the 15 sections and for securing theseveral sections together.

Another object of the invention is the provision of a circuit breaker embodying a casing of ceramic insulating material with an improved mounting arrangement for the actuating mechanism in which a base plate mounted within the casing supports the actuating mechanism and is formed to provide stops for the switch lever so as to relieve the casing of impact stresses during operation of the breaker.

Another object of the invention is the provision of an improved circuit breaker that is simple and rugged, safe and reliable in operation, which is extremely compact so that it occupies a relatively small amount of space, and which can be manufactured at a relatively low cost.

The novel features that are considered characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to structure and operation, together with additional objects and advantages-thereof, will best be understood from the following detailed description of several embodiments thereof when read in connection with the accompanying drawings, in which:

Figure 1 is a vertical sectional view of H the circuit breaker embodying the features of the invention; a

Fig. 2 is a fragmentary view of the breaker with a portion of the casing broken away and parts shown in section to illustrate certain mounting features of the invention;

Fig. 3 is a horizontal sectional view of the breaker shown in Fig. 1 taken on the line III-III thereof and looking in the direction of the arrows;

' Fig. 4 is a fragmentary sectional view of the breaker illustrating the actuating mechanism in the open circuit position;

Fig. 5 is a fragmentary sectional view similar to Fig. 4 illustrating a modified form of the ac tuating mechanism;

Fig. 6 is a diagrammatic view of a slightly modified arrangement of the actuating mechanism shown in Figs. 1 and 4;

Fig. 7 is a fragmentary detail view illustrating the two part switch lever and biasing springs in end elevation;

Fig. 8 is a top plan view of the main frame showing the manner in which the supporting lever for the toggle links and the latching lever are pivotally mounted thereon; and

Fig. 9 is a fragmentary plan view of the base plate showing the stop means for the switch lever.

Referring to the drawings, the circuit breaker illustrated comprises a casing indicated generally at H which consists of an intermediate base section IS, a cover or end section I 5 and a supporting end section I], all of ceramic insulating material. The supporting section I1 is provided with a threaded contact shell IQ of conducting material and a center contact 2| located adjacent the lower end of the supporting section. The contact shell I9 and the center contact 2| form the terminals of the circuit breaker, the breaker being of the type that is supported by an electrical socket which serves to connect the breaker in an external electrical circuit. The supporting sec tion is also provided with a chambered recess 23, in which is disposed an electromagnetic means indicated generally at 25. The electromagnetic means 25 serves to trip the breaker open upon the occurrence of heavy overload currents or short circuit conditions in the controlled circuit and also acts as a magnetic blowout means for moving and extinguishing the are drawn between the gontacts of the breaker during circuit interrup- The electromagnetic means comprises a coil 21 which is wound upon an insulating spool 29, a stationary core 3! and a cooperating movable core 33, both of magnetic material. The stationary core 3! and the movable core 33 are enclosed by a sleeve 35 disposed within the central opening of the spool 29. The lower end of the sleeve 35 is provided with an inturned flange which limits downward movement of the movable core.

An adjusting means is provided for varying the tripping point of the electromagnet 25. The adjusting means comprises an adjusting screw 31 threaded in the movable core 33 and a compression spring 39 disposed between the inturned flange at the lower end of the sleeve 35 and the head of the screw.

The stationary core Si is provided with a central cylindrical opening through which extends a thrust rod 4i the lower end of the thrust rod extending near the movable core 33 while the upper end of the thrust rod extends through a cylindrical opening provided in the intermediate base section i3. The thrust rod H is adapted to be moved upwardly when the movable core 33 is attracted in response to a heavy overload or short circuit condition to trip the breaker open in a manner which will be described hereinafter.

The intermediate base section I3 is provided with a recess 43 over the electromagnetic means 25 which forms a switch chamber. 'Disposed within the switch chamber 43 are a pair of spaced stationary contacts 45 and a movable yoke-shaped bridging contact 41, which cooperates with the stationary contacts to open and close the circuit.

main frame.

The movable contact 41 is adapted to be moved by the actuating mechanism in a horizontal plane to open and close the circuit through the breaker. It will be noted that the path of movement of the movable contact is at right angles to the axis of the electromagnet 25, so that the magnetic flux produced by the electromagnet acts to move and extinguish the are drawn between the contacts during circuit interruption.

A base plate 4! is secured to the upper surface of the intermediate base section l3 and covers the switch chamber formed therein. Mounted on the base plate I! is a main frame 5| consisting of a pair of spaced side plates 53 (Figs. 2 and 8). The lower ends of the spaced plates 53 are bent outwardly at right angles and are adapted to be secured to the base plate U, as shown in Fig. 2.

The actuating means of the circuit breaker comprises, in general, a pivoted multiple arm switch lever indicated generally at 55 the lower end of which is connected to the movable contact H, a pair of toggle links 51 and 59, a pivoted supporting lever SI for supporting one end of the toggle formed by the links 51 and 59, a pivoted latching lever 53 for releasably engaging and restraining the supporting lever in operative posi tion, a closing push button for closing the breaker, and a release push button 51 for opening the breaker, both of insulating material. The supporting lever 5| (Fig. 8) is pivotally supported on the main frame by means of a transverse pivot pin 69, which extends through openings provided therefor in the side plates 53 of the The lever BI is provided with an integral U shaped bearing portion H extending at right angles to the lever portion 13 thereof. The bearing portion H is provided with openings which engage the pivot pin 69 at two bearing points outside of the side plates 53 of the frame, the lever arm 13 of the supporting lever being disposed outside of the main frame. It will be noted that the bearing points of the bearing portion H of the supporting lever 5| are spaced apart a greater distance than the effective lever arm 13 of the supporting lever.

The toggle links 51 are pivotally connected at one end by means of a pivot pin 15- with the upper end of the multiple arm switching lever 55. The opposite ends of the toggle links 51 are pivotally connected to one end of the toggle link 59 by means of a knee pivot pin Tl, while the opposite end of the toggle link 59 is connected to the bearing portion H of the supporting lever 6| by means of a pivot pin 19.

The latching lever 53 is pivotally supported on the main frame by means of a pivot pin 80 in substantially the same manner as the supporting lever H.

The latching lever 63 is provided with a U shaped bearing portion Bl having openings which engage a transverse pivot pin 80 outside of the main frame 5!, and an angular lever arm portion 33 disposed outside of the main frame in the same manner as the supporting lever Bl. The

upper end of the latching lever 63 is notched, as

indicated at 35, and engages the free end of the supporting lever il, as best shown in Fig. 1. The latching lever 53 thus normally serves to hold the supporting lever 6| in a normal or operative position to maintain and support the right-hand end of the toggle in an operative position. The latching lever 53 is adapted to be moved in a counter-clockwise direction about its pivot pin 80 to eflect release of the supporting lever GI to tri the breaker in a manner which will hereinafter be described.

The push button 85 is mounted for vertical movement on the frame 5| by means of upper and lower guide plates 81 and 89 which extend transversely between the side plates 53 of the main frame, the upper plate 81 being provided with an opening for receiving and guiding the upper end of the push button 85, which projects through an opening provided therefor in the cover I5. 1

A vertically disposed plate 9| is secured to the lower end of'the push button 85 by having a portion thereof embedded in the insulating material of the push button. The plate 9I is provided with an elongated horizontal slot 92 which engages the knee pivot pin 11 of the toggle links, so that the push button 85 is thus connected to the toggle links. The plate 9I is also provided with a depending leg 93 which passes through an opening provided therefor in the lower guide plate 89. The guide plates 81 and 89, in addition to guiding the push button 85, also serve to limit the movement thereof by reason of the fact that the plate 9| engages the guide plate 81 in the open circuit or outer position of the push button and engages the lower plate 89 in the closed circuit or inner position of the push button 85 as best shown in Figs. 1 and 5.

The multiple arm switch lever 55 (Figs. 1 and 7) comprises an upper yoke-shaped arm 95 and a lower yoke-shaped arm 91, both arms being pivoted about a common pivot pin 99 supported by the main frame. The bridge portion IOI which bridges the legs of the lower arm 91 serves as a stop to limit clockwise rotation of the upperarm 95 with respect to the lower arm. The lower ends of the legs of the lower arm 91 are pivotally connected to the movable contact 41 by means of a pivot pin I00, the contact member being held against lateral shifting movement on the pin I by spacers I02 (Fig. 7).

A spring I05, which is coiled about the pivot pin 99, serves to bias and maintain the arms 95 and 91 in the extended position, as shown in Figs. 4 and 5, in which the upper arm 95 engages the bridging member IOI of the lower arm 91. A spring I01, which is coiled about the pivot pin 15 connecting the toggle links 51 with the upper arm 95 of the switch lever 55, serves to bias the toggle links 51 in a counter-clockwise direction about the pivot pin 15. It will thus be seen that the spring I01 serves to bias the toggle formed by the links 51 and 59 to their collapsed position, and the closing push button 85 to its outer open position, as shown in Figs. 4 and 5.

A spring I 09, which has its ends secured to the side plates 53 of the main frame, part of its body portion coiled about the pivot pin 99,

Y and the remaining portion engaging the upper arm 95 of the switching lever 55, serves to bias the switching lever in a clockwise direction about the pivot pin 99 to its open circuit position.

The release push button 81 is connected with the latching lever 83 by means of a release rod II I and a pivoted transfer lever H3. The lever H3 is pivotally mounted intermediate its ends on the main frame by means of a transverse pivot pin II 5 (Fig. 1). The right-hand end of the lever H3 has a reduced end portion II1 which engages in an opening provided therefor in the bearing portion 8i of the latch lever 83. The release rod III has the release push button 81 secured to its upper end while the lower end thereof is offset and has a reduced end portion which fits in an opening provided in the lefthand end of .the transfer lever H3. The release rod III and push button 51 are held in mounted position by the cover I5. A biasing spring II9 engages the underside of the transfer lever III on the left side of its pivot pin H5. The biasing spring II9 serves to maintain the latching lever 83 in latching position in which its notchedfree end engages and holds the'support lever Si in normal position. The spring H9 also serves to bias the release rod III and the push button 81 in an upward direction to their normal position, as shown in Fig. 1. The novel manner of connecting the lower end of the release rod III to the transfer lever I I3 and the right-hand end of the transfer lever H3 to the bearing portion 8| of the latching lever 83 eliminates the necessity of any connecting pivot pins and thus reduces the manufacturing cost of the breaker.

The manual operation of the circuit breaker is briefly as follows: With the breaker in closed position, as shown in Fig. 1, let it be assumed that it is desired to manually open the breaker. The push button 81 is manually depressed to cause downward movement of the release rod III. The downward movement of the release rod III moves the transfer lever H3 in a counter-clockwise direction about its pivot pin H5. The counter-clockwise rotation of the transfer lever H3 moves the latching lever 83 in a counter-clockwise direction about its pivot pin 80 to effect release of the supporting lever 8I. When the supporting lever 8| is released, the

biasing force exerted by the spring I09 acting on the multiple arm switch lever moves the switch lever to open circuit position to open the contacts and also moves the toggle links 51 and 59 toward the right, as viewed in Fig. 1, to partially rotate the supporting lever 6| in a counterclockwise direction'about its pivot pin 59. The slot 92 permits the knee pivot pin 11 of the toggle links to be moved to the right as the toggle links are moved to the right by the switch lever. After the switch lever 55 has been moved to open circuit position under the influence of the biasing spring I09, the force exerted by the spring I01 moves the toggle links 51 in a counterclockwise direction about the pivot pin 15 to effect collapse of the toggle and outward'movement of the push button 85, as shown in Fig. 4. This movement of the toggle to the collapsed position returns the push button 55 to its normal open circuit position and also rotates the supporting lever 8I in a clockwise direction about its pivot pin 19 to its normal position, as shown in Figs. .1 and 4. Following release of the push button 81, the biasing spring II9 acts to return the latching lever 83 to its latched position in which it re-engages the supporting lever 8|. The

circuit breaker is now in the open circuit posi tion and the parts have been reset for the next circuit closing operation.

To close the breaker, the closing push button 85 is manually depressed and this movement of the push button causes the upper edge of the slot 92 to move the knee pivot pin 11 of the toggle links 51 and 59 downwardly through its deadcenter position to the position shown in Fig. 1, in which the knee pivot pin 11 lies below the line joining the pivot pins 15 and 19. The movement of the toggle comprising the links 51 and 59 to its "in toggle position moves the multiple arm switch lever 55 in a counter-clockwise direction about its pivot pin 99 from the open position shown in Fig. 4 to the closed position shown in Fig. l to move the movable bridging contact 41 to closed circuit position in engagement with the stationary contacts 15. Whe the contacts are closed and the switch lever 55 is in the closed circuit position, the force exerted by the biasing spring I09 maintains the toggle comprising the links 51 and 59 in its in toggle position, since this force exerted by the spring I09 is greater than the force exerted by the spring I01 which tends to collapse the toggle.

During the circuit closing operation previously described, as the toggle comprising the links 51 and 59 is moved by the push button 65 to its in toggle position, the upper arm 95 of the multiple arm switch lever 55 is rotated in a counter-clockwise direction about the pivot pin 99 relative to the lower arm 91 of the switch lever. This relative movement of the upper arm 95 with respect to the lower arm 91 of the switch lever stresses the spring I05 to store energy therein. After sufficient energy has been stored in the spring i05 it moves the lower arm 91 of the switch lever in a counter-clockwise direction to closed circuit position with a snap action to close the contacts. The spring i05 also serves to maintain a predetermined contact pressure between the movable contact 81 and the stationary contacts 45 in the closed circuit position of the breaker.

During a circuit opening operation, the force exerted by the biasing spring I09 and that exerted by the biasing spring I05 moves the upper arm 95 of the switch lever in a clockwise direction about the pivot pin 99 until the legs of the lever engage the bridging member IOI of the lower arm 91. During this movement, considerable kinetic energy is stored in the upper moving arm 95 so that this kinetic energy, together with the force exerted by the spring 109 on the upper arm 95 of the switch lever, moves the lower arm 91 from the closed circuit position shown in Fig. 1 to the open circuit position shown in Fig. 4 with a snap action to open the contacts.

It will be noted that the connecting means between the closing push button 55 and the knee pivot pin 11 of the toggle links renders the switch lever 55 and movable contact 41 trip-free of the closing push button. That is to say, the slot 92, which connects the push button 55 to the knee pivot pin 11 permits the switch lever 55 to be moved to open circuit position under the influence of the biasing spring 209 following release of the supporting lever SI, even though the push button 55 is manually held in the depressed position. 4

A thermally responsive trip means is provided for causing automatic opening of the circuit breaker in response to lower magnitude overloads of predetermined value and duration in the circuit controlled by the breaker. The thermally responsive trip means comprises a U-shaped bimetallic trip element I2I which has its legs secured to the intermediate base section 13 by means of a pair of terminal bolts I23. The upper free end of the bimetallic trip element I2I is provided with an adjusting screw I25 which engages an insulating member I24 secured to a projection on the bearing portion SI of the latching lever 53. The insulating lever I24 serves to insulate the latching lever from the bimetallic trip element i2i. The bimetallic trip element l2I when heated a predetermined amount in response to an overload of sufficient duration flexes in a direction toward the actuating mechanism. This flexing movement of the bimetallic trip element moves the latching lever 53 in a counter-clockwise direction about its pivot pin 80 to effect release of the supporting lever SI and opening of the breaker in the same manner as when the push button 01 is depressed.

Upon the occurrence of a heavy magnitude overload or short circuit condition in a circuit controlled by the breaker, the movable core 33 is moved upwardly by the electromagnet 25. This upward movement of the core 33 moves the thrust rod ll in an upward direction to engage and move the transfer lever H3 in a counter-clockwise direction about its pivot pin II5. This counter-clockwise movement of the transfer lever II=3 rotates the latching lever 53 in a counterclockwise direction about its pivot :pin 80 to effect release of the supporting lever BI and opening of the breaker in the same manner as when the release push button 51 is depres'sedas has been previously described.

The circuit for the breaker extends from the contact shell I9, through a conductor I21 to one terminal screw I23, through the bimetallic trip element I2I to the opposite terminal screw I23, through the stationary contact 45, movable contact 41 opposite stationary contact 45 and by means of a conductor I29 to one end of the coil 21, through the coil and from the opposite end of the coil through a conductor I3I to the center contact 2I.

The side plates 53 of the frame 5I, the hearing plate 49 and the spool 29 of the electromagnet 25 are all secured to the intermediate base section I3 by means of a plurality of hollow tubular rivets I33, as shown in Fig. 2. vThe cover or end section I5 and supporting section I1 are removably secured in clamped relation to an intermediate base section I3 by means of a plurality of bolts I35 which pass through openings provided in the supporting section I1 and the cover or end section 15, the body portion of the bolts extending through the hollow tubular rivets I33. The heads of the bolts I35 engage the shoulders of the countersunk openings I31 provided in the supporting section I1, while the nuts I39 for the bolts are disposed in recesses provided in the cover or end section I5.

The base plate 49, which is secured to the upper surface of the intermediate base section I3, is provided (Fig. 9) with a pair of notched recesses Ill for receiving the legs of the lower arm 91 of the switch lever 55. The ends I43 of the recesses form stops for limiting the movement of the switch lever 55 and also function to relieve the casing II from any direct impact stresses during the operation of the circuit breaker.

If desired, the lowermost guide plate 89, which bridges the side walls 53 of the main frame, may be positioned a considerable distance below the dead-center position of the knee pivot pin 11, as shown in Fig. 6. The advantage of this construction is that during a manual circuit closing operation when the push button 05 is depressed a sufficient amount to move the knee pivot pin 11 below its dead-center position, the force exerted by the biasing spring I09 acts to move the knee pivot pin of the toggle downwardly until the vertically disposed plate 9I, which is secured to the push button 65, engages the lowermost stop 89, so that immediately after the knee pivot pin 11 crosses dead-center position, the force exerted by the spring I09 acts to pull the push button 65 downwardly so that the latter glides by and moves ahead of the finger during the circuit closing operation. This arrangement prevents false or improper operation of the cirzuit breaker and provides a desirable safety feaure.

A modification of the actuating mechanism for the circuit breaker is illustrated in Fig. 5. The actuating mechanism of the modification shown in Fig. 5 is identical in all respects to the actuating mechanism described in connection with Fig. 1, except that a pivoted latch member I45 is provided for normally releasably holding the lower arm 91 of the multiple arm switch lever 55 in the open circuit position, as shown in Fig. 5, until the push button 65 has been moved downwardly a predetermined distance. The latch I45 is pivotally supported on the main frame by means of a pivot pin I41 and is biased to latching position by means of a spring I49. The nose of the latch member I45 engages the bridging member IIlI, which connects the legs of the lower arm 91, when the switch lever is in the open circuit position. The tail-piece of the lever I45 is located directly below the depending projection 83 which is carried by the push button 65 so that after the push button has been moved downwardly a predetermined distance the projection 93 engages the tail-piece of the latch I45, and further downward movement of the push button 65 moves the latch member I45 to its released position to efiect release of the lower arm 91 of the switch lever 55. The operation of this modified form of operating means is briefly as follows: To close the breaker, the push button 65 is moved downwardly. During the first partof the downward movement, the toggle formed by the links 51 and 59 is moved to the in toggle position, as shown by the dotted lines in Fig. 5. This movement of the toggle to the extended or in toggle position rotates the upper arm 95 of the switch lever 55 in a counterclockwise direction about'the pivot pin 99 to stressand store energy in the spring I05 which connects the upper arm 95 with the lower arm 91. At thispoint of the movement of the push button 65, the depending projection 93 carried thereby engages the tail-piece of the latch member I45. Further movement of the push button moves the latch member I45 in a clockwise direction about the pivot pin I41 to effect release of the lower arm 91 of the switch lever. The energy stored in the spring I05 following release of the lower arm 91 moves the arm to closed circuit position with a snap action to close the contacts of the breaker. This form of actuating means positively prevents improper operation of the circuit breaker, since no matter how slowly the push button 65 is depressed, the contacts are closed with a snap action when the push button has been-moved a predetermined amount.

. tofore been considered possible.

From the above description it will be seen that the invention provides an improved circuit breaker that is compact, safe and reliable in operation, and which can be manufactured at a relatively low cost.

While the invention has been shown and described in accordance with the provisions of the patent statutes, it is to be understood that various changes in structural details thereof may be made without departing from the spirit of the invention. It is desired, therefore, that the appended claims be given the broadest reasonable construction in the light of the prior art.

I claim as my invention:

1. In a circuit breaker, a movable switch member for opening and closing the circuit,.actuat-- ing means for the switch member includinga multiple link toggle connected at one end to,

the switch member and having its other end normally supported in operative position by a movable support, a movable operating member having a portion provided with a longitudinal slot for engaging the knee pivot pin of the toggle which connects the operating member and toggle and provided with outer and inner shoulder portions, frame means for supporting the actuating means comprising a pair of spaced side walls between which the operating member and toggle are disposed, and a pair of spaced plates extending transversely between said side walls having openings for guiding the operating memmovable push button operating member connected to the knee of the toggle for moving the toggle from collapsed position through deadcenter position. to a made position to close the circuit, stop means for limiting inward and outward movement of the operating member, said toggle when moved through dead-center position toward its made position acting to pull said operating member inwardly under the influence of said spring means to prevent improper closing operation of the breaker, said inner stop being so positioned as to permit said push button to be pulled in through a substantial portion of the latter part of its inward movement by said toggle.

3. In a circuit breaker, a movable contact member for opening and closing the circuit, actuating means for moving the contact member to open and closed position including a pivoted double arm switch lever consisting of a pair of arms pivoted about the same fixed axis, means including a spring coupling said arms for movement together, said spring. tending to resiliently maintain said arms in the same predetermined angular position with respect to each other at all times, one of said arms being connected with said switch member and the other with said actuating means, said actuating means including electro-responsive means operable to cause said actuating means to eflect circuit opening movement of said contact member.

4. In a circuit breaker, contact means for opening and closing the circuit, actuating means for opening and closing said contact means ineluding a pivoted multiple arm switch lever consisting of a pair of arms pivoted about the same axis to a fixed support, means including a spring coupling said arms for movement together, said spring acting to resiliently maintain said arms in the same predetermined angular position with respect to each other at all times, one of said arms being connected to said contact means and the other of said arms to said actuating means, said spring means serving to provide a predetermined contact pressure when the contact means are closed and acting as an accelerating spring to secure quick make and break action of the contact means during operation of the breaker, said actuating means including electroresponsive means operable to cause said actuating means to effect opening of said contact means.

5. In a circuit breaker, contact means for opening and closing the circuit, actuating means for opening and closing said contact means including a pivoted multiple arm lever consisting of a pair of arms pivoted about the same axis to a fixed support, means including a spring coupling said arms for movement together, said spring acting to resiliently maintain said arms in the same predetermined angular position with respect to each other at all times, one of said arms being connected to said contact means, releasable latch means for restraining said last mentioned arm against closing movement when said contact means are open, a movable operating member for moving the other arm of said lever to close the circuit, said operating member having means for automatically releasing said latch means to free the arm connected to said contact means at a predetermined point in the closing movement of said operating member, said actuating means including electroresponsive means operable to cause said actuating means to open said contact means.

6. In a circuit breaker, relatively movable contact means, a rigid frame having spaced side walls, actuating means for opening and closing said contact means having elements thereof disposed between the side walls of said frame and connected at one end to said contact means, a lever having a U shaped bearing portion straddling the side walls of said frame and pivoted at 3 two spaced bearing points to the side walls of said frame, and having an arm disposed at the outside of one of said side walls, said lever being movable from a normal position to a tripped po sition to cause said actuating means to effect opening or" said contact means.

'7. In a circuit breaker, relatively movable contact means, a rigid frame having spaced side walls, actuating means for opening and closing said contact means including a toggle disposed between the side walls of said frame and connected at one end to said contact means, a lever having an arm disposed adjacent one of said side walls and a U-shaped portion provided with two spaced bearing portions pivoted to the side walls of said frame to pivotally mount said lever, said lever being movable from a normal position to a tripped position to cause said actuating means and toggle to effect opening of said contact means, said spaced bearing portions of said lever being spaced apart a greater distance than the effective lever arm of said lever.

8. In a circuit breaker, relatively movable contact means, a. rigid frame having spaced side walls, actuating means for opening and closing said contact means including a toggle disposed between the side walls of said frame and connected at one end to said contact means, a carrier lever pivoted to said frame for supporting the other end of said toggle, said lever having a lever arm disposed adjacent one of the side walls of said frame, a latching lever pivoted to said frame having a lever arm disposed adjacent said one side wall of said frame for normally engaging the arm of said carrier lever to restrain said carrier lever in operative position, said carrier lever and said latching lever each having two bearing portions spaced apart a greater distance than their effective lever arms and pivoted to thespaced side walls of said frame.

9. In a circuit breaker, relatively movable contact means, a rigid frame having spaced side walls, actuating means for opening and closing said contact means including a toggle disposed between the side walls of said frame and connected at one end to said contact means, a carrier lever pivoted to said frame for supporting the other end of said toggle, and a latching lever pivoted to said frame for normally restraining said carrier lever in operative position, said levers having lever arms normally engaged one by the other disposed at the outside of one of said side walls, and said levers each having a U shaped bearing portion straddling the side walls of said frame and pivoted to the side walls of said frame at two bearing points spaced apart a greater distance than the effective lever arm of the lever, said latching lever being movable to release said carrier lever to cause opening of said contact means.

10. In a circuit breaker, relatively movable contact means, a fixed frame having spaced side walls, actuating means for opening and closing said contact means having elements thereof disposed between the side walls of said frame, a pivoted latch lever movable from a latching position to an unlatched position to cause said actuating means to open said contact means, said lever having a latch arm disposed adjacent one of the side walls of said frame to one side of the actuating means, and having a U-shaped bearing portion pivotally supported at two spaced bearing points on the side walls of said frame, and means operable 'to apply force to the U-shaped portion of said lever between the spaced pivot points thereof to move said lever to unlatched position.

HANS H. WILLMANN. 

